Purification of diolefins



. in the'case of light'oil butadiene fractions, v butyle'ne may be regarded as an'impurity if the Patented Apr 117, I945 mans TENT;

PURIFICATION on moments Frank J. Soday, Swarthmore, Pa, assignor to The, United Gas Improvement Company, a corporation of Pennsylvania -No Drawing.

Application February 18, 1943, Serial No. M6334 l8 creams. (Cl. zen-681.5)

.In general, this invention relates to the purification of unsaturatedhydrocarbons.

More particularly, this invention relates to the separationof pure or relatively pure diolefins from Iractions or mixtures containing, the said diolerins. An object of the present invention is the purification of diolefins by a combination of processes, each designed to remove certain undesirable materials. Another "object of the invention is the isolation of pure or relatively pure diolefins from fractions or mixtures containing the same by processes comprising the application of specific refining operations designed to remove certain of the impurities present, followed by concentrating op}- erations designed to remove most, or substantially all, of the diluents present. Other objects and advantages of the invention will be apparent to those skilled in the art uponan inspection of the specification and claims.

The material present in diolefiniractions or 1 mixtures, other than diolefins, may be divided into This distinction is somewhat artificial in character, but it is based upon functional considerations. Consequently, it possesses considerable significance 'from the standpoint of the industrial applications. of'tli zdiolefins in question.

It is recognized t regarded as an imp In. rtain applications and as a diluent in other pplicatlons. I Th.

butadiene is to beused in the production of synthetic rubber, whileit may function only as a diluent in certain other applications.

In general, it may be said that the compounds classed as'impurities seriously aflect the quality or'yield of the product to be obtained from a given reaction. Thus, inthe polymerization or copoly- Inerization of one or" more dloleflnsito form syntial reduction in yield. In general, the impurities act as catalyst poisons, polymerization inhibitors,

chain reaction interruptors, and the like.

Diluents, on the other hand, are less'specific in their action, and generally afiect the nature and/ or extent of the polymerizing reaction to a somewhat less marked degree than the materials classifled previously as impurities. -In general, they serve to reduce the reactivity of the diolefin or mixture of dloleflnsby reducing the concentration of uch material in the reaction Zone.

This must not be taken to mean that they do not deleteriously affect the yield or quality of the diolefin below 98%, practically no product being obtained at concentrations below 80 In general, it may besaid that the materials classified as impurities generally are present in dlolefin fractions and/or mixtures in rather limited quantities, frequently comprising less than ven-jeompound may be 5% and, in many cases, less than 1% of the total mixture. Diluents, on the other hand, may be present in much larger quantities, and may comprise the principal component or components in the diolefin fraction and/or mixture.

Thus, a representative light oil butadiene free-'- tion may contain butadiene, 25% isobutylene, 22% other butylenes, 2% butanes, 1% acetylenic hydrocarbons, 0.1% aldehydes, and smaller amounts or other oxygenated impurities, sulfur compounds, and nitrogencompounds.

I have discovered that fractions and/or mix- .tures containing one or more diolefins, .impurities, and 'diluents may be processed to obtain the diolefin or mixture of diolefin in a pure or subthetic rubber, the presence thereinfifof substantial quantities of acetylenic. compounds, aldehydes,

halogen-containing compounds, and/or similar impurities, usually results in theproduction of a verylnferior product, and/or a very substanstantially pure state by subjecting the said fraction or mixture to refi'ning operations to remove the desired proportion, or substantially all, of the impurities present, followed by the application of concentrating processes designed to remove subrities present, thus substantially reducing the losses normally encountered due to polymerization, and/or other causes, during this operation, a

' well as to the absence, or reduction in quantity of, certain impurities during the subsequent concentrating operation, thus preventing, or retardobtained by the use of finely trating reagent.

A. preferred embodiment of this invention is the removal of controlled quantities of certain impurities during the initial refining operations. Thus, in the case of acetylenic hydrocarbons, I frequently preierto control the refining operations to give an intermediate product contaim ing, say, 6.75 to 6.25% of acetylenic hydrocarbons, particularly when the subsequent concentrating operations are of a type tobe more particularly described herein. In such concentrating operations the acetylenic hydrocarbons act as polymerization inhibitors, the presence of which in small quantity may be desired. The concentration operations are of such character as to give a prodnot containing a negligible proportion of acetylenio hydrocarbons.

The diolefin fractions and/or mixtures which may be improved by my process may beobtained from any desired source such as synthetically, for

by condensation and fractionation, or the pyrolysis of terpenic hydrocarbons; and by the pyrol ysis of other materials, such as by the pyrolysis of cyclic hydrocarbons, for example cyclohexane, or by the pyrolysis of alcohols, such as for example the pyrolysis of ethyl alcohol. In the latter case, the process ma include a combination of dehydrating and/or pyrolytic reactions.

Thus, for example, in the preparation of "butadiene, two important basic raw materials are petroleum, or petroleum hydrocarbons such as C4 hydrocarbons, and ethyl alcohol.

Due to the relatively large proportions of impurities present in the butadiene obtained from ethyl alcohol, particularly oxygenated impurities, the method disclosed is unusually well adapted to treating the crude product obtained from such material.

- It is to be understood, of course, that the mixtures and/or fractions obtained from the foregoing operations may contain more than one diolefin, and that such mixture of diolefins may be isolated in more pure form by the method'disclosed herein prior to any separation of such diolefins.

Although the method i adapted to the refining of diolefins, and particularly conjugated diolefins,

in general, I find it to be particularly applicable to the refining of fractions and/0r mixtures con-- taini'ng one or more diolefin's selected from a list I consisting of butadiene, isoprene,-. andpiperylene.

The first stage of the operation for the production of pure or relatively pure diolefins Etrom dilute fractions and/or solutions containing the same, namely, the removal of impurities, may be carried out in a number or ways.

A preferred method for removing the impurialloys thereof. Particularly desirable resultsarex' alkaline earth metals.

divided alkali and in an inhibitor. 7

The use of a polymerization inhibitor is of barasvavis ing the rate of, the deterioration of the concen- Such operations preferably are carried out in a continuous manner and in the presence of polymerization. inhibitors. Reference is made to my copending applications Serial No. 457,743, filed September 9, 1942, Serial No. 460,688, filed October 3, 19412, and Serial No. 476,333, filed February 18, 194.3. 7

Examples of refining metals which may be used for such purpose are lithium, sodium, potassium, rubidium, caesium, barium, strontium and calcium. Due to the availability and low cost oi sodium and potamium, however, these metals are preferred for the use set forth herein. 7

Alloys of these metals, such as Naibio, NaCas, Nazniz, KNa, and the like, also may be employed for the removal of undesired impurities from diolefin fractions and/or mixtures. In general, the alloys of the respective metals react with the impurities present in such fractions and/or mixtures at a slower rate than the correspending metals, I

1h general, therefore, it maybe said that very finely divided metals in group Ia and Ila of the periodic system, and theirreactive alloys, may be used to refine unsaturated hydrocarbons and unsaturated hydrocarbon fractions witl'f very satisfactory results, particularly in the presence of one or more polymerization inhibitors.

Examples of polymerization inhibitors are (l) secondary aryl amines such as phenyl beta-naphthyiamlne, diphenyl-p-phenylene diamine, isopropoxydiphenyl amine, aldol-a.lpita-no.phthyl amine (and polymers thereof), symm. alt-beta naphthyl-p-phenylene diamine, trirnethyldilly droquinoline (and polymers thereof), and the ditolylamines; (2) phenolic compounds, such as p-tertiary butyl catechol and allrylated polyh droxy phenols; and (3) reaction products a ketone, such as acetone, and/or an aldehyde, such as formaldehyde and acetaldehyde, with amine, such as aniline.

In general, I prefer to employ less than li by Weight, of polymerization inhibitor, on the unsaturated hydrocarbon or unsaturated hy drocarbon fraction in batch treating processe. and the maximum total volume of suspending liquid in the treating system at any one time in the case or continuous treating processes. Good results also have been obtained by the use of less than 5% inhibitor and even 2% inhibitor in cer tain cases, particularly when one or more of the inhibitors listed in the preceding paragraph are employed.

I find that a solution of sodium, or a suspension or emulsion of. very finely divided sodium, or a solution, suspension, or emulsion of one or more sodium alloys, is a particularly desirable agent -'for the continuous removal of certain undesir-q able impurities from diolefin fractions and/or mixtures, particularly when carried-out in the presence of at least one polymerization inhibitor. Excellent results are obtained by the use of a suspension. of very finely divided sodium containticular importance in the caseof dioleflns, such as butadiene, which are quite susceptible to polymerization when placed in contact with certain active metals, as .well as active alloys thereof.

Thus, sodium is a very active catalyst for the polymerization of butadiene and-fisfemployed for this purpose in several industrial ro'cesses, notfably in Russia. The -use of this material in very finely divided form for the refining of butadiene,

therefore, must beicarriedout; within well de- -fined limits in order toprevent undue loss of butadiene due to polymerization. 'The success of the refining method employing finely divided sodium. or other active metals, or alloys, depends to a veryconsiderable extent upon the presence-therein of a polymerization inhibitor." It will .be understood, of course, that an inhibitor must be 'very specific and powerful in actionin order to retard the rate of polymerization of unsaturated hydrocarbons, such as butadiene, in

the presence of a very active catalyst, such as finely divided sodium.

The refining operations may be carried out in any desired -manner such as batch, multiple derstood that, generally speaking, the refining process is not limited to anymethod of operation.

Although the continuous refining operations also may be carried out in any desired manner, I prefer to conduct it in a vertical vessel or tower in which a certain height of a liquid suspension or solution of the active refining agent, preferably containing an inhibitor, is maintained. The material to be refined is passed upward through this column of reagent at a ratesufiicient to insure the removal. of the desired quantity and type of impurities present at the temperature employed. Reference is made to my copending application,

Serial No. 457,475, filed September 5, 1942.

Other methods of contacting the material to be treated and the refining reagent also may be librium conditions'had been established was 76% butadiene fraction and 24% xylene.

The material being treated also may serve as a suspending medium for the refining reagent without the addition of any other material, if desired. Thus a light oil" butadiene fraction may -be introduced into the desired tower or vessel,

togetherwith the finely divided refining agent and'inhibitor, after which the butadiene fraction is passed into the suspension of the refining agent in the butadiene fraction at the desired temperature, the charging rate and more particularly-the operating pressure being adjustedto maintain the refining agent at the desired level in the vessel.

It is tobe understood, of course, thatthe portion of the material to be treated which has been dissolved in the suspending medium or which has been employed as the suspending medium in the substantial absence of other liquid materials,

does not necessarily remain in the treating zone throughout the entire treating cycle. Rather, this material is in a state'of dynamic equilibrium with the material being treated, a portion of it volatilizing continuously and being removed from the system, the material volatilized in this manner being replaced by the solution of a corresponding quantity of freshly added material to be treated. The major portion of the materialto be treated, of course,- bubbles up throughthe'suspending medium without dissolving therein.

The thickness of the layer of refining reagent through which the material to be treated is preferably passed depends upon a number of factors, such as the quantity and type of impurities present, the type and quantity of inhibitor employed, the extent to which such impurities are to be removed, the type and degree of dispersion of the treating agent employed, the reaction temperature, the concentration of the treating agent in the suspending medium, and the like. In genany of the constituents of the refining reagent or the material to. be treated to any substantial extent, and provided that it' does not introduce eral, however, I prefer to employ a layer of refining reagent at least one foot thick and, more preferably, at least two feet thick. Excellent results are obtained by the use ofa layer of refining reagent at least four feet thick.

It'will be recognized that,-other things being equal, the depth or refining reagent employed in the treating vessel controls the contact time between the material tojbe refined and the refining reagent. w

The degree of dispersion of the treating agent also has a very profound effect upon the degree of "refining obtained. In the case of sodium, .I prefer to employ a subdivided mass inwhich at least the majority of the particles present have ation of the process usually'comprises a-mixture of the material to be treated and-'- the suspending medium initially introduced into. the system. Thus, in the treatment of a light oil lrutadiene fraction with a xylene suspension of finely divided sodium containing an inhibitor in a con-'- tinuous system operating at 50 C. and. atmospheric pressure, the suspending medium contained 11% of the butadiene fraction by weight after equilibrium conditions had been established.

In a similar manner, when refining a light oi1- butadiene fraction in a continuous system with of 50 pounds per square inch, gauge, the vcom--.

a diameter oi not more than 0.05" and, more preferably, not more than 0.03". Excellent results are obtained when at least the majority of the particles present have a diameter of not more than 0.02". This subdivision may be carried out in any desired manner. Thus, in the case of sodium, a

solution of this material in liquid ammonia may be introduced nto an inert liquid, such as xylene,"

dispersing ability of the spray nozzle employed,

position of the suspending, medium after equiof an are between sodium electrodes in an inert liquid.

Although almost any desired concentration or treated, upon an hourly basis, are passed through the suspending medium.

It will be recognized that the contact time be tween the material to be treated and the reagent is determined both by the thickness of the layer of refining reagent employed and by the rate at treating agent in the suspending medium maybe employed, depending upon the type and concen tration of the fraction to be refined, the torn erature, the depth of reagent employed, and the like, I generally prefer to employ a refining re-= agent containing less mar-130%, and more par ticularly less than by weight of the treating agent. Excellent results are obtained when less than 15% by weight of the treating agent is suspended in the suspending medium.

It is to be understood'of course, thatthe term suspending. medium refers to the actual suspending agent employed during the treating operation,

and includes any of the material being treated which may dissolve in such agent.

The type and concentration of the diolefin fraction and/or mixture to be treated also has a considerable influence upon the method of operating the process. Thus, with a highly concentrated butadiene, such as 98% butadiene, the refining reagent should preferably contain a fairly low concentration of active agent, and a. fairly high concentration of inhibitor, to minimize losses due to polymermation.

I generally prefer to employ a fraction of such concentration, and with such proportion of suspending medium; that the actual concentration of diolefin, such as butadiene, in the reaction zone is less than 80%, and, more preferably, less than Excellent results are obtained when the actual concentration of unsaturated hydrocarbon in. the reaction zone is less than 60%.

The process may be carried out at any desired pressure, such as atmospheric, subatrnospheric, and superatmospheric pressures.

The temperature at which the process is conducted also has a very considerable bearing upon the degree towhich the fraction is refined and the losses incurred due to polymerization. Although. the optimum reaction temperature to be employed is dependent largely upon other factors,

.s-uch as the concentration of both the diolefin and the refining reagent in the reaction zone,'I generally preferto conduct the refining operationsv at temperatures below 100 C.' ghmore partic larly, below 80 0. -Excellent r ts are obtaine by conducting the refining operatlonsat temperatures' below 70 C. The rate at which thema- 'terial to be refined is passed through the refining reagent has a very considerable effect upon the degree to which the impurities present are red, although this is dependent to some extent other variables such as the concentration of.,. refining agent in the suspending medium and the temperature at which the refining operations are being-conducted. While it is difilcult to establish exact limits for optimum throughputs under all conditions, I'generally prefer not to exceed'a throughput of material to be; treated on an hourly basisof more than four times the weight of suswhich the material to be treated is passed through the reagent.

The method employed for introducing the material to be refined into the refining reagent also has some influence upon the extent to which the dioleiin fraction and/or mixture is defined;

Ir general, it may be said that a [line stream or jet of the liquid or gaseous material to be refined is desired. This may be accomplished by introducing the material to be treated into the refining reagent by means oi suitable orifices, jets, nozzles, or other subdividing means. Porous objects or materials also may be employed for this purpose, such as porous ceramic or glass diifusing blocks or units.

its the refining agent may show some tendency to settle out in the bottom of the treating vessel ,or unit, the jets or nozzles by means or which the material to be treated is introduced into the unit may be so arranged as to prevent any undue settling'of thismaterial. In vertical vessels, this may be accomplished by locating these units in such a way as to'impinge the inlet stream or streams upon the bottom of the treating vessel. The inlet jets also may be arranged tangentially to impart a swirling or circular motion to the refining reagent, if desired. Another method comprises locating the inlet jet or jets 7 directly in the bottom of the reactor, or tangentially in the sides of the reactor, or both, to prevent any settling in the bottom of the reacting vessel and/or to impart any desired circular or other motion to the refining reagent.

Any desired combination or these methods aiso may be employed, such as the use of a jet or jets directly impinging upon the bottom of the reactor in conjunction with the use of a tam" gential jets or jets to prevent the active agent from settling out and depositing on the walls or" the reactor and/or to maintain the refining reagent in any desired state of'agitation.

The refining reagent also may be maintained in the desired degree of agitation by the use 0: suitable stirring or mixing devices, or by the use of circulating pumps, or by a combination of these methods, or otherwise. One or more or these methods also may be used in conjunction with one or more of the methods discussed previously to maintain the'syst-em in the desired degree of dispersion.

It should be pointed out, however, that the used such agitation methods is not required in pending medium employed and more preferably,

not more than twice the weight of the suspending medium. Excellent ,results'are obtained when not more than equal quantities or material to be most cases. Thus, excellent results have been secured by. conducting the refining operations in a tower, the material to be treated being introduced into the bottom of the tower by means of a small orifice. .The passage of the fraction being treated in the gaseous state upward through the column was found to maintain the system in the desireddegr'ee of agitation. A

.The refining agent, particularly when finely divided sodium is employed forthis purpose, usually acts both as a reactant and as a polymerizing agent for the removal of undesired impurities. Thus, in the case of light oil butadiene fiactions containing monovinylacetylene, other acetylenes, aldehydes,' and other oxygenated impurities, the sodium will react with atleast a portion of the monovinylacetylene present to asrsms form sodium monovinylacetylide, and may react with certain of the oxygenated derivatives to form corresponding derivatives. At least a portion of the acetylenic hydrocarbons present also are polymerized to form polymers, or copolymers ly and the second in a discontinuous manner.

with other unsaturated hydrocarbons present,

which frequently are insoluble in nature. Cerbe removed in any desired manner, such as by filtration, which may be carried out continuously during the refining operation, or may be I carried out in a batchwise manner'after the ter-' mnation of the refining step.

As the removal of the insoluble-polymers also is attended by some loss of refining agent, even I when the latteris in a very fine state of .sub-

d vision, itis advisable in many cases to continue the refining operations until the'refining agent h s been largely or completely exhausted before filtering.

.The solid or, semi-solid filtered products may be treated to recover any desired materials or they may be disposed of in any suitable manner. ThusJany unchanged refining agent, such as sodium. may be recovered by melting and coalescing operations. or by amalgamation with mercury, or otherwise. such as sodium monovinyl acetylide and/or other metallic acetylides, may be decomposed with water to regenerate the corresponding acetylenes or they may be reacted with carbon dioxide to form unsaturated acids, or otherwise. Any inhibitor present also may be recovered.

A convenient method for the disposal of the insoluble polymers comprises treatment with carbon dioxide, suitably in the presence of trace of, moisture. followed by filtration. i

' As the. cost of the treating process is largely a function of the ouantity of the reactiv agent employed in the refining operations, the efilcient utilization of such agent is of considerable imnortance. A .desirable method for insuring optimum utilization of the treating agent is to carry out'the operations in a continuous countercurrent manner. the reagent moving through the system in a manner countercurrent to that oi? the material to be, treated.

This may be illustrated by means of a consideration of a simple continuous countercurrent system comprising two treating towers or vessels.

The material to be treated is passed into the first which it is discarded and the partially exhausted Certain of the reaction products,

This may be modified such as by the continuous addition of fresh reagent to the-second tower, the continuous transfer of partially exhausted reagent to the first tower, and the continuous withdrawal of more completely exhausted, or exhaust ed, reagent from the first tower. A completely continuous countercurrent treating system thus is achieved. Y

Any desired modification of these methods'may be employed, and any number of treating towers or units may be used. It will be observed that in I each ofthe cases discussed, the incoming material to be refined is contacted with partially exhausted reagent (maximum concentration of impurities-minimum concentration 7 ofactive agent), while the outgoing material to be refined is contacted with fresh or more highly conc'entrated reagent. (minimum concentration of impurities-maximum concentration of active agent); Thus'the two objectives to be sought, namely, practically complete, or complete, utilization of the active agent and substantial, or practically complete, removal'of impurities from the material to be refined, are achieved.

As the limiting factor affecting the utilization of the active agent is the proportion of insoluble polymers and/or residues which can be contained therein without seriously impairing its flowing properties, or the passage of. the gaseous material to be treated therethrough, it frequently happens that the quantity of insoluble material present is "insufiicient'to interfere seriously with the operamay be continued until the concentration of insoluble material in the refining reagent renders it too viscous to be used further in the process in asatisfactory manner. j

In this connection, it is well to point out that the insoluble products formed during the reaction have a tendency to stabilizthe sodium suspension and act to reduce the rate of settling of the finely divided sodium in certain cases, As this is desirable, the incomplete removal of insoluble products from the refining reagent may be indicated, or even the addition of a certain quantity of such materials to a fresh reagent.

Soluble polymers also usually are formed in small amounts during the refining operationa As certain of these soluble and/or liquid polymers are converted on prolonged contact with the refining reagent to viscous and/or insoluble products,'their removal from the suspending medium, suitably at the 'end of a refining cycle and prior to the return of the suspending agent to the system, may be'indicated. On the other hand, cer-' tain 'of these soluble polymers are sufilciently stable to act as a. suspending medium for the refining agent.

Having removed the impurities present'to the desired extent by the use of one or more of the refining methods described previously, the next step in the process comprises the application oi.

reagent from the second column substituted for it. Fresh reagent then is added to the second suitable concentrating processes designed to remove the diluents present to yield a product having the desired concentration. 7

This may include concentration by fractionation, solvent extraction, azeotropic distillation, or

a combination of azeotropic distillation and solvent extraction methods.

countercurrent to each other, the first continuous cellent results have been obtained by the latter reagent.

Solid dry salts of metals or groups 16 and Iib of subdivision during at least The concentrating operations include contact:

'ing the diolefin fraction and/or mixture with one or more salts oi. metals of groups It: and 11b of v the periodic system. The minor mixture or salts used for this purpose may be inthe i'orm 'of a solution in a suitable solvent, in the form of a suspension or slurry in a suitable organic or inorganic liquid, or in the term or solid, Thus, for example, a solution of cuprous acetate in water containing relatively small quantities of ammonia; a suspension or slurry of cuprous chloride in water; or solid, dry, finely divided cuprous chloride may be employed for this purpose. E1:-

the use of dry salts.

desirable results are obtained when at least the major ortion'of the dry reagent salt comprises particles having a diameter of less than 005mm. and, more particularly, less than 0.03 mm. mien better results are obtained when at least the major portion or the dry reagent salt comprises particles having a diameter of less than 0.02 mm. and particularly less than 0.01 mm.

A particularly desirable method. for the production and maintenance of the dry reagent salt in the desired state of very fine subdivision comprises conducting the operations in a ball or rod mill. Additional means to maintain a relatively clean surface on the mill at all times, such as by the use of a scraping agitator, a plow or other device; by the use of irregularly-shaped I grinding objects; and/or by the .use of a double salts under suitable temperature and pressure conditions, which complex or association product may be afterward dissociated, usually after separation from the unreacted material, to liberate the diolefins and regenerate the reagent salt;

Such dissociation or decomposition may be carried out by an increase in temperature and/or a reduction in pressure. a

Monovalent cuprous salts are very desirable agents for use in concentrating processes of this type due to their stability, ease orregeneration, low cost, and availability.

purpose.

Under suitable conditions of temperature and pressure, conjugated dioleflns may be made to react with reagents or the type described in prelerence to other unsaturated hydrocarbons.

Thus, the conjugated diolenns present in a given, mixture chloride under conditions oi. temperature and pressure such that substantially only conjugated diolefin materials are absorbed by thereaction mass. Then after removal of unreacted hydrocarbon material, the complex formed between the conjugated diolefins and the cuprous chloride may be decomposed by elevation in temperature and/or reductionin pressure to liberate the conjugated diolefins in concentrated form and revivify the reagent.

As described and claimed in my'copcnding application, Serial No. 457,187 filed September 3, 1942, the efiiciency of such solid dry'reagent salts is increased substantially by the incorporation or an anhydride thereof, such as an oxide of an therein of an organic or inorganic basic substance Cuprous chloride is a 1 particularly desirable salt tobe used for this may be contacted with cuprous conical ball mill, also may be employed, if desired. The exact conditions employed tor the concentration of diolefins by the use of salts-o! metals of group Ib and Ilb of the periodic system will vary somewhat with the character of the salt employed, a well as the method in which it is used. When employing solid, dry, finely divided cuprous chloride tor this purpose, the absorption commonly is carried out at temperatures below 25 0., and more particularly below 20 C., while the desorption'operations usually are carried out at temperatures above C. When operating under reduced pressures, somewhat lower desorption, or decomposition, temperatures may be employed.

The process may be further illustrated by means of the following example.

Example A light oil butadiene fraction containing 50% butadiene, 25% isobutylene, 21% butylenes, 2% butanes, 1% acetylenic hydrocarbons, 0.0 4% aldehydes, and small quantities of other impurities was passed continuously into the bottom of a 2" steel column containing a xylene suspension of very finely divided sodium at a temperature of 50 C. and a pressure of 50 pounds per square inch, gauge. The treating medium contained 0.05% ct a substituted polyphenolas a polymerizatlon inhibitor.

Under theoperating conditions employed, the

actual suspending medium was a mixture of 2 4% alkali metal and/or an oxide of an alkaline earth metal, in conjunction with an inhibitor, such as a secondary aryl amine, a polynuclear phenol, a polyhydroxy phenol, and/or a substituted phealdehyde or a ketone with an amine.

As described and claimed inmy copending application, Serial Number 460,692, filed October nolic material; and the reaction product. or an 3, 1942, such processes maybe carried out in a particularly desirable manner when the dry reagent salt is maintained in an unusually fine state the initial phases of the absorption operations. Thus, exceptionally of xylene and 76% of the butadienefraction. The quantity of finely divided sodium employed was grams, representing a 7% suspension in the indicated sus'pendingmedium.

The run was continued for a total of 31 hours at an average charging rate of 840 grams per hour, the total, quantity of butadiene fraction charged being approximately 2400 grams.

Only very small traces of the butadiene, butylones, and butanes were'removed during the refining operation. However, the acetylenic hydrocarbon content was reduced to 0.02%, the aldehydes to 0.001%, and the remaining minor impurities substantially completely removed.

The refined butadiene fractions is contacted with a mixture of 97.5 parts of finely divided, dry cuprous chloride, 2% calcium oxide and 0.5% phenyl-beta-naphthylamine contained in a ball mill provided with two scraping agitator blades for a period 0- 25 C; and a pressure of 0-60 lbs. per square inch; After removing unreacted material, the

which is very suitable for the production or synthetic rubber. The olefin and paraifine porinsuring of 20 minutes at a temperature of prising contacting said mixture, with tion of the charge stock, listed previously as unreacted material, is obtained in the form of a fraction containing only 5% butadiene.

' In' the specification and the claims, the follow-- ing terms have the indicated meanings.

Thev term "polymerization inhibitor is intended to include one or more compounds or materials which serve to retard, or entirely prevent, the polymerization of unsaturated hydrocarbonsin the resence of an active refining agent.

The term metals of group Ia. and group IIa of the periodic system" is intended to mean lithium, sodium, potassium, rubidium, caesium, barium, strontium, and calcium, as well as active alloys containing one or more of such metals as an essential ingredient.

The term finely divided is intended to mean having a diameter of less than 0.05", as well as materials in the colloidal or dissolved form.

In the specification and claims the term addition compound" i;intended to include the reaca mixture containing the same comprising concompound.

4. A process for the recovery'of piperylene from tactingsaid mixture withat least one of a grpup consisting of finely divided metals of groups Ia and 11a of the periodic system followed by con tacting the remaining mixture. with at least one solid, dry monovalent salt of a metal of groups Ib and IIb of the periodic system under conditions suitablefor the formation of an addition compound between the said salt and the said piperylene, separating the unreacted material from the addition compound, and decomposing the said addition compound. I

. 5. A process for obtaining a more highly refined conjugated diolefin from a mixture containing a material reduced to such a state of fineness that .the preponderating part is composed of particles the same comprising contacting said mixture with finely divided metallic sodium in the presence of a polymerization inhibitor, followed by contacting the remaining mixture with finely divided, dry cuprous chloride containing a polymerization inhibitor.

tion product of oiie or more dioleflns with a reactive salt or compound, the said addition compound regenerating the diolefin or diolefins when heated above a-certa in temperature level, 7 While various procedures have be'enparticularfstoodth'at the foregoing specific examples are given by way of illustration and that changes,"

omissions, substitutions, and/or modifications might be made within the scope of the claims without departing from the spirit of the invention.

I claim: 1. A process for the recovery of diolefins from .ly described these are'of course subject to co'n- .siderable variation. Therefore, it will be under fvided cuprous chloride.-

6. A process for obtaining amore highly refined conjugated "diolefin from a mixture containing the same comprising contacting said mixture with a hydrocarbon suspension of finely divided metalli-c sodium in a continuous system, followed by contacting the remaining mixture with finely di 7. A'process for recovering a conjugated diolefin in more concentrated and less contaminated form s from a mixture of said conjugated diolefin with impurity and diluent, comprising contactingsaid a mixture containing at least one diolefin comconsisting o ely divided metals of groups In and 11a of the periodic system followed by'contacting the 'remaining'mixture witha t least one solid, dry monovalent salt ofa metal of groups 111 and 11th of the periodic system under-conditions tacting said ggzture with at least one of a group suitable tor the formation of an'additio'n compoundbetween the said salt and the 'sald butadiene separating the unreacted material from the 'ad-. dition compound and decomposing the said addition compound.

'3. A process for recovery of isoprehe from a i mixture containing the samecomprising contacting said mixture with at least one of a group conslsting of finely divided metals of groups Ia and nc of the periodic system followed by contacting.

- the remaining mixture with at least one sold,

dry monovalent 'salt 01' a metal ofgroups Ib and 11b of the periodic system under'c ondit'ions suitable-for the formation of an addition compound between the said salt and the said isoprene, separating the unreacted material from the addition at least contaminated and diluted conjugated diolefin with at least one of a group consisting of finely divided metals of groups Ia and Ilia ofthe periodic systemto remove at least aportion of said im purity, contacting the. remainingmixture containing said conjugated diolefin in less contaminated form with at least one monovalent salt of a metal of groups Ib and 11b of the periodic system under conditions suitable'for the formation'of an addition compound between said salt and said conjugated diolefinic' material, separating unreacted material comprising at least a portionof said diluent from the addition compound, and decomposing said addition'comp'oun'd to re-' cover said conjugated diolefin is less contamihated and more concentratedforrnI 8. A process for purifying a conjugated diolefin contained in admixturewith impurity and diluent,

comprising contacting said, admixture with at least one of a group consisting of finely 'divided I metals of groups Ia and 11a of the periodic system to remove at leastaportlon of said impurity followed by contacting the remaining admixture with at least one monovalent salt of copper under conditions suitable tor the formation of an adf dition compound between said salt and said conjugated 'diole flnic' material, separating unreacted materiab'containing at least ajportion of said diluent trom theaddition compound, and decomposing said addition compound 'to recover ,sai'dfl conjugated diolefin in more concentrated and less contaminated form.

9. A process for recovery of'a conjugated di-- olefin from. a mixture containing the same in'admixturewith impurity and diluent, comprising contacting. said mixture with at leastibne of a group consisting of finely divided metals groups Ia and 11d of the periodic system to! move at least aportion of. said impuritmfollowedby contacting the remaining mixtureWith solid'dry cu.- Prous chlorlde under temperature conditions be-'- compouni and decomposing the "said addition low C., to form a conjugateddiolefin-cuprous chloride complex, separating unreacted'material including at least aportion of said diluent from said complex, and decomposing said complex under temperature conditions above C. 10. A process for the recovery of a conjugated diolefin from a mixture containing the same in admixture with impurity and diluent, comprising continuously. passing said mixture at a temperature below 80"0. through a dispersion of at least one finelydivided metal selected from the group consisting of metals of groups Ia and Ila of the periodic system, said dispersion containing a polymerization inhibitor, and containing less than 20% by weight thereof of said finely divided metal and being at least two feet in thickness in'the direction of flow of said mixture, the con centration of said conjugated diolefin in the reaction zone "being less than 70%, while maintaining a rate of flow per hour of said mixture through saiddispersion of less than twice the weight of dispersion medium employed thereby removing I at least a portion of said impurity, and thereafter contacting the remaining mixture with a monovalent salt of copper under conditions suitable for the formation of an addition compound be tween said salt and said conjugated diolefin, saparating unreacted material containing at least a portion of said diluent from said addition compound.

ll. A process for the recovery of a conjugated diolefin from a mixture containing the same with pound, and decomposing the said addition cornimpurity including acetylenic material and with diluent, comprising continuously passing said mixture under temperature conditions below 80 C. through a dispersion of at least one finely divided metal selected from the group consisting of metals of groups Ia and Ho of the periodic system, saiddispersion containin a polymerization inhibitorand containing less than 20% by weight thereof, of said finely-divided metal and being at least two feet in thickness in the directionof flow of said mixture, the concentration of said conjugated diolefln in the reaction zone being less than 70%,. while maintaining a rate of flow per' hour of said mixture through said dispersion of less than twice the weight of dispersion medium employed thereby removing at least a portion of said lmpuritylncluding acetylenic material, followed by contacting the remaining mixture with solid dry cuprous chloride under temperature conditions below 20 C. to form a conjugated diolefin-cuprouschloride complex, separating unreacted material including at least a portion of said diluent from said complex, and thereafter decomposing said complex under temperature conditions above so c.

' ticles of which have a diameter of not more than 0.03", said dispersion containing a polymerization inhibitor and containing less than 20% by weight thereof of said finely divided sodium and being at least two feet in thickness in the direction of flow of said mixture, the concentration ofsaid conjugated diolefin in said reaction zone being lessthan 70%, while maintaining a rate of flow per hour of said mixture through said disperslon of less than twice the weight of dispersion medium employed thereby removing at least a portion of said impurity including acetylenic material, and contacting the mixture containing said conjugated diolefin in less contaminated form with a monovalent salt'or copper under conditions suitable for the formation of an addition compound between saidsalt and said conjugated dioiefin, separating unreacted material containing at least a portion of said diluent from said addition compound, and thereafter decomposing the said addition compound to recover said conjugated dioleiin in more concentrated and less contaminated form. v

13. A process for the purification of a com jugated diolefin contained in admixture with impurity including acetylenic material and with diluent, comprising continuously passing said admixture at a temperature below 100 C. through a dispersion of finely divided sodium containing a polymerization inhibitor and being at least one foot in thickness in. the direction of flow or" said admixture, said dispersion containing less than 36% by weight thereof of said finely divided sodium and the concentration of said conjugated diolefin in the reaction zone being less than 80%, while maintaining the rate of flow per hour of said admixturethrough said dispersion at less than four times the weight of dispersion medium employed thereby removing at least a portion of tion of which is in the form of acetylenic material and diluent at least a portion of which is in the form of 'olefinicmaterial, comprising contzriing said light oil conjugated diolefin fraction with finely divided potassium to remove at least -a portion of. said impurity including acetylenic material, contacting the remaining-fraction with .at least one monovalent salt of copper under conditions suitable forthe formationoof an addition compound between said salt and said conjugated idiolefinic material, separating unreacted material including at least a portionof said olefinic material from the addition compound, and decomposing said addition compound to recover said conjugated diolefin in'less contaminated and more concentrated form.

15. A process for purifying a light oil butadiene fraction containing butadiene and containing impurity at least a portion of which is in th form of acetylenic material and diluent at least a portion of which is in the form of olefinic material, comprising contacting said fraction with finely divided sodium to remove at least a portion of said acetylenic material, followed by contacting the remaining fraction with at least-one monovalent salt of copper under conditions for the formation of an add tion compound between said-salt and said butadiene, separating unreacted material containing at least a portion of said olefinic ma terial from the addition compound, and the eafter decomposing said additon compound to recover said butadiene in more concentrated and less contaminated form.

16.1 process ior puriiying a lightoil isoprene fraction containing-isoprene and con tion of which is in theform i olefinic material,

comprising said fraction with finely divided-sodium to remove at least a portion of' said acetylenic-material, followed by contacting the remaining fraction with atleast one mono valent salt of' copper under conditions for the formation 01' an addition compoundbetween said saltand said isoprene, separating unreacted material containing atleast a portion of saidoletlnic 'material'irom the addition compound, and thereafterdecomposing said addition compoundto 'recov'er saidisoprene iii-more concentrated and less contaminatediorm." p

i7. Aprocessforpuriiying a light oil piperylene' fractioncontainingpiperylene and containing impin-ity at least a portion-oi which-is in the form of acetylenic material and diluent at least aPQrtion oi 'whichfis in i'orm'ofoleflnicmaterial, com 4 prising'contactlng said fraction with ilnely divided to remove at least 1a portion of said acetylenicrz material, followed by contacting the remaining fraction with at least one monovalent-salt oi'.. copperunder conditions for the formation of an addition -compound between said salt and said material con- 1 purity at least a portion 0! which is in the form "of acetylenic material and diluent at least a porm m I t 9 piperylene in more concentrated and less contaminated i'orm.

1s. a process s the purification of a light n coniugated dioleiin fraction containing a coniusated diolefln together with impurity at least a portion oi. which is in the form oi acetylenic material anddiluentatleastaportion'oi' w'hichisin the form 01' Oleflnic material, comprising continuously passing said fraction at atemperature 10 below 80 0. through a dispersion of finely divided 4 sodium, said dispersion containing a polymerization inhibitor-and containing less than by weight thereof of said finely divided metal and being at least two feet in thickness in the direction is or flow of said traction, the concentration or said coniusated diolefln in the reaction zone'being less than while maintaining a rate of flow per hour oi said traction through said dispersion of ,less than twice the weight of dispersion medium 2oemplo yed thereby removing at least a portion of said acetylenic material. thereafter contacting the portion with solid dry cirprous chloride under conditions suitable for the formation or an addition compound between said salt" and said 'zil oniugated-d'ioleiln; separating unreacted ma-' terial including at least a portion oi said oleflnic material from said addition compound, and decomposing said addition compound to recover said coniunited diolefln in more and less 7 sonsYfg 

